Former President Barack Obama reacts as he walks on stage at a rally in support of candidate for Senate Jacky Rosen and other Nevada Democrats, Monday, Oct. 22, 2018, in Las Vegas. (AP Photo/John …

Former President Barack Obama reacts as he walks on stage at a rally in support of candidate for Senate Jacky Rosen and other Nevada Democrats, Monday, Oct. 22, 2018, in Las Vegas. (AP Photo/John Locher)